Recently, slant plate type compressors such as a wobble plate type compressor have become greatly in demand in automotive air conditioning systems. The structure of such compressors is well known in the industry and is shown in FIG. 13. Typically, slant plate 50 is disposed on drive shaft 26 at an angle relative thereto. The rotary motion of drive shaft 26 and slant plate 50 is converted into a wobbling motion having a longitudinal component parallel to drive shaft 26 by wobble plate 60, which is coupled to slant plate 50. The wobbling motion of wobble plate 60 is then translated into a reciprocating motion of pistons 71. Balance ring 90 or annular balance weight is disposed about slant plate 50 to maintain the balance of slant plate 50 as it rotates.
Balance ring 90 is affixed to a boss 54 on slant plate 50. In the typical compressor, wobble plate 60 is disposed between slant plate 50 and balance ring 90. Wobble plate 60 is rotatably mounted on slant plate 50 through bearings 81 and 62. The thrust race 80, is disposed between wobble plate 60 and bearing 81. Because slant plate 50 and balance ring 90 rotate relative to wobble plate 60 and because there is no direct coupling between wobble plate 60 and balance ring 90, collisions often result between wobble plate 60 and balance ring 90. The gap between wobble plate 60 and balance ring 90 is at a maximum when piston 71 is at a top dead center and at a minimum when piston 71 is at a bottom dead center. This is primarily due to the fact that the pressure reaction force of the piston is at a maximum at the top dead center and a minimum at the bottom dead center. As shown in FIG. 13, the minimum gap is indicated as C.sub.1 and the maximum gap as C.sub.2.
Accordingly, as a result of collisions between wobble plate 60 and balance ring 90, offending noises are generated during compressor operation. This noise is especially remarkable when the compressor is rotating in low speed at high pressure ratio, although the magnitude of the noise level varies with change in the operating condition of the compressor. In addition, the collisions between wobble plate 60 and balance ring 90 cause unnecessary wear and shorten the life span of these parts.
One solution to solve the problem of colliding wobble plate 60 and balance ring 90 is to reduce the gap therebetween. However, it is difficult to manufacture the compressor so that the gap is within the desired tolerance. Furthermore, seizure of the compressor is possible if the gap between wobble plate 60 and balance ring 90 is rigidly reduced. Therefore, it is desirable to provide a compressor with a substantially eliminated or reduced gap between the wobble plate and the balance ring to reduce incidents of collision therebetween while maintaining the operating integrity of the compressor.